void G_CDECL font (int nfont, ...) FNTPLT.C Level 1
int nfont The number of fonts selected, where nfont is between 1 and 4. 
This is followed by up to four pairs of optional arguments:
char *font_name The name(s) of the font(s) to be selected must be in double quotes. This routine takes a variable number of arguments, so you only need to provide the font name and escape symbol for the first nfont arguments. 
The GraphiC unfilled fonts are: 
simplex.fnt, simgrma.fnt, complex.fnt, compital.fnt, compgrma.fnt, engoth.fnt, triplex.fnt, tripital.fnt, duplex.fnt, russian.fnt, simscr.fnt, comscr.fnt, microg.fnt, microb.fnt, block.fnt.
GraphiC filled fonts are:
swiss.fnt, swissitl.fnt, swissbld.fnt, swissbit.fnt, swissn.fnt, news.fnt, newsgrm.fnt.
Or any installed PostScript Type 1 (.PFB file names) or TrueType (.TTF font names)  font may be used. 
char esc# A single character which, when placed in a string, will activate font#. The character must be in apostrophes. It is best to use a character from the second half of the ASCII set (above 199) since then all of the characters in each set are available for use. These characters are entered by holding down the Alt key and typing the character # on the numeric keypad. An easy choice to remember is characters 201 204. Your C compiler may not allow direct entry of characters above 127, so in this case, octal characters must be used. A convenient choice is '\300'  '\303'. The characters used as escape characters cannot be plotted by GraphiC.
Up to four fonts may be activated at once. Each font uses about 5 to 10 kb of memory, so you may wish to use fewer fonts to conserve memory. If fewer than four fonts are selected, you can skip the remaining arguments. nfont must be the number of actual font styles specified. GraphiC, PostScript, and TureType fonts may be intermixed.

For example:

font(1,"c:\\gpcnt\\complex.fnt",'\302', "c:\\psfonts\\TIB_____.PFB", '\303')
The font selection may be changed at any time by calling font() again.